III-V semiconductor core-heteroshell nanocrystals

Abstract

The present invention provides a core/multishell semiconductor nanocrystal comprising a core and multiple shells, which exhibits a type-I band offset and high photoluminescence quantum yield providing bright tunable emission covering the visible range from about 400 nm to NIR over 1600 nm.

1. A core/multishell semiconductor nanocrystal, comprising:
 a core material comprising a III/V compound; and 
 at least two shell materials, comprising
 a first shell material that coats the core material, 
 a second shell material that coats the first shell material, and sequentially each subsequent shell material coats a preceding shell, 
 each shell material independently comprising a compound selected from a II/VI, a III/V or a III/VI compound, the core material being different from the first shell material, and any shell material is different from a shell material of an adjacent shell, 
 
 wherein the nanocrystal exhibits a typed band offset and luminescence at a wavelength from about 400 to about 1600 nm, and 
 wherein a band gap of the core material is less than a band gap of the first, second and any subsequent shell materials, the band gap of the first shell material is larger than the band gap of the core material and lower than the band gap of subsequent shell materials, and the band gap of the second or any subsequent shell material is larger than that of the first or preceding shell material and lower than the band gap of any subsequent shell materials. 
 
     
     
       2. The core/multishell semiconductor nanocrystal according to  claim 1 , wherein between 2 and 7 shell materials are present. 
     
     
       3. The core/multishell semiconductor nanocrystal of  claim 1  being an undoped nanocrystal. 
     
     
       4. The core/multishell semiconductor nanocrystal according to  claim 1 , consisting of the core material, the first shell material and the second shell material and the first and second shell materials are different materials. 
     
     
       5. The core/multishell semiconductor nanocrystal according to  claim 1 , wherein the III/V compound is selected from the group consisting of InAs, InP, GaAs, GaP, GaSb, InSb, AlAs, AlP, AlSb, InGaAs, GaAsP, and InAsP. 
     
     
       6. The core/multishell semiconductor nanocrystal according to  claim 5 , wherein the core material is InAs, InP or GaAs. 
     
     
       7. The core/multishell semiconductor nanocrystal according to  claim 1 , wherein the at least two shell materials are II/VI compounds. 
     
     
       8. The core/multishell semiconductor nanocrystal according to  claim 1 , wherein the at least two shell materials are III/V compounds. 
     
     
       9. The core/multishell semiconductor nanocrystal according to  claim 1 , wherein the at least two shell materials are III/VI compounds. 
     
     
       10. The core/multishell semiconductor nanocrystal according to  claim 7 , wherein the II/VI compounds are selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdZnSe, CdSSe and ZnSSe. 
     
     
       11. The core/multishell semiconductor nanocrystal according to  claim 8 , wherein the III/V compounds are selected from the group consisting of InAs, GaAs, GaP, GaSb, InP, InSb, AlAs, AlP, AlSb, InGaAs, GaAsP and InAsP. 
     
     
       12. The core/multishell semiconductor nanocrystal according to  claim 9 , wherein the at least two shell material III/VI compounds are selected from the group consisting of InS, In2S3, InSe, In2Se3, In4Se3, In2Se3, InTe, In2Se3, GaS, Ga2Se3, GaSe, Ga2Se3, GaTe, Ga2Te3, In2Se3-xTex, GaTeSe and (GaxIn1-x)Se3, wherein X is zero or 1. 
     
     
       13. The core/multishell semiconductor nanocrystal according to  claim 1  being selected from InAs/CdSe/ZnS, InAs/CdSe/CdS, InAs/InP/ZnSe, InP/ZnSe/ZnS, InP/CdS/ZnSe, InP/CdS/ZnSe, GaAs/CdSe/ZnS, and GaAs/CdS/ZnS. 
     
     
       14. The core/multishell semiconductor nanocrystal according to  claim 1  being InAs/CdSe/ZnSe or InP/ZnSe/ZnS. 
     
     
       15. A wideband optical amplifier for amplifying data-carrying optical signals, comprising a plurality of the core/multishell semiconductor nanocrystals according to  claim 1 , wherein each of the core/multishell nanocrystals has core dimensions that correspond to a specific optical band and is located at a predetermined point within a light transmitting medium; and a pumping, coherent-light source connected to said light transmitting medium for exciting each of the nanocrystals with light energy required for the amplification of data-carrying optical signals within the specific optical band, received in the light transmitting medium. 
     
     
       16. A light-emitting diode comprising a plurality of the core/multishell semiconductor nanocrystals according to  claim 1 . 
     
     
       17. A biological labeling agent comprising a plurality of the core/multishell semiconductor nanocrystals according to  claim 1 . 
     
     
       18. A photoelectric device comprising a plurality of the core/multiple shell semiconductor nanocrystals according to  claim 1 . 
     
     
       19. A laser device comprising a plurality of core/multiple shell semiconductor nanocrystals according to  claim 1 . 
     
     
       20. An optical data communication system comprising a plurality of the core/multiple shell semiconductor nanocrystals according to  claim 1 . 
     
     
       21. A host material containing a plurality of the core/multishell semiconductor nanocrystals according to  claim 1 . 
     
     
       22. The host material according to  claim 21  being a polymer. 
     
     
       23. The host material according to  claim 22 , wherein the polymer is selected from the group consisting of fluorinated polymers, polymers of Ployacrylamide, polymers of Polyacrylic acids, polymers of Polyacrylonitrile, polymers of Polyaniline, polymers of Polybenzophenon, polymers of poly(methyl mathacrylate), silicone polymers, Aluminium polymers, polymers of Polybisphenol, polymers of Polybutadiene, polymers of Polydimethylsiloxane, polymers of Polyethylene, polymers of Polyisobutylene, polymers of Polypropylene, polymers of Polystyrene and Polyvinyl polymers. 
     
     
       24. The host material according to  claim 23 , wherein the polymer is selected from polyvinyl and fluorinated polymers. 
     
     
       25. The host material according to  claim 24 , wherein the polymer is polyvinyl-butyral or Perfluorocyclobutyl. 
     
     
       26. A plurality of the core/multishell semiconductor nanocrystals according to  claim 1 , having luminescence at a wavelength from about 400 to about 1600 nm. 
     
     
       27. A method for the manufacture of a core/multishell semiconductor nanocrystal, according to  claim 1 , having at least two shells, comprising:
 (i) providing a core, 
 (ii) contacting the core with a solution of a first soluble cation or soluble anion selected from Group IIIa, IIa, Va or VIa ions, allowing the cation or anion to react on the core, 
 (iii) contacting the core with a counterion, selected from Group IIIa, IIa, Va or VIa ions, of the first soluble cation or soluble anion solution of step (ii) and allowing the counterion to react and afford a core/shell 1  structure, 
 (iv) contacting the core/shell 1  structure with a solution of a second soluble cation or soluble anion, selected from Group IIIa, IIa, Va or VIa ions, allowing the cation or anion to react on shell 1  of the core/shell 1  structure, 
 (v) contacting the core/shell 1  structure with a second counterion selected from Group IIIa, IIa, Va or VIa ions, of the second soluble cation or soluble anion solution of step (iv) and allowing to react and afford a core/shell 1 /shell 2  structure, 
 (vi) optionally repeating steps (ii) to (v) with one or more further solution of a further soluble cation or soluble anion and subsequently a counterion of the further soluble cation or soluble anion to form a core/multishell semiconductor nanocrystal of a higher order 
 wherein the core/multishell is undoped and exhibits luminescence at a wavelength from about 400 to about 1600 nm. 
 
     
     
       28. The method according to  claim 27 , wherein the core/multishell exhibits a type- 1  band offset. 
     
     
       29. The method according to  claim 27 , further comprising the steps of isolating the core/shell 1  and the core/shell 1 /shell 2  structures. 
     
     
       30. The method according to  claim 27 , wherein the first soluble cation solution is selected from Cd and Zn. 
     
     
       31. The method according to  claim 27 , wherein the first soluble anion solution is selected from S, Se and P. 
     
     
       32. The method according to  claim 27 , wherein the second soluble cation solution is selected from Zn and Cd. 
     
     
       33. The method according to  claim 27 , wherein the second soluble anion solution is selected from S and Se.